Scott McTominay was involved in a bust-up with Neymar in the first-half of the game.
The Red Devils suffered a disappointing 3-1 defeat at the hands of qualification rivals PSG.
Brazilian midfielder Fred headbutted Leandro Paredes in the 1st half for which he was lucky to receive just a yellow card.
But he was later sent off after picking up a harsh booking for a foul on Ander Herrera in the second half.
In the first half, McTominay was involved in a heated squabble with Neymar, following a full-blooded tackle on the Brazilian forward.
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“Yeah. Tough one, you know. With the way they act on the pitch, the way they conduct themselves,” the Scotland international told Esporte Interativo.
“Sometimes I feel like it’s difficult to accept the way… obviously in terms of how the game panned out with the referee and the decisions that were made. I have nothing to comment on that. I think it’s poor.
“I feel like the way we were feeling in the dressing room now is not good for a reason, and that’s out of our control with things that happen on the pitch.”
“But as I said, difficult game, we were the better team in my opinion, so for us we have to look to Saturday,” McTominay added.
“We have to bounce back, we have to keep that positive momentum, I thought we were the better the team, throughout the whole game we created some brilliant chances.
“In football you have to take them, if not, you get punished.”